Air gun

ABSTRACT

AIR GUN FOR SCARING BIRDS AND OTHER UNDESIRABLE CREATURES, COMPRISING AN ELONGATED RESERVOIR WHEREIN A PLURALITY OF BALLS IS STORED AND WHICH CAN BE PRESSURIZED. THE BALLS ARE EXPELLED ONE BY ONE WHEN THE AIR PRESSURE IN THE RESERVOIR ATTAINS A VALUE CAPABLE OF FORCING ONE BALL THROUGH AN ORIFICE IN THE RESERVOIR WALL, OVERCOMING THE RESISTING FRICTIONAL FORCE BETWEEN THE ORIFICE AND THE BALL. EITHER THE BALLS OR THE ORIFICE WALL CAN BE MADE ELASTIC OR DEFORMABLE WHILE THE OTHER ELEMENT IS MADE RELATIVELY RIGID OR NON-DEFORMABLE. IN A PORTION OF THE RESERVOIR, VERTICALLY ALIGNED ABOVE SAID ORIFICE, IS A PADDLE MEMBER WHICH IS KEPT SIDEWAYS BY THE JET OF AIR WHICH OPERATES THE GUN, UPON THE PASSAGE OF A BALL THROUGH SAID ORIFICE. THE RESERVOR IS ASSOCIATED WITH AN AUXILIARY RESERVOIR, BY WAY OF A NARROW PASSAGE, FOR ALTERNATIVELY STORING AND DELIVERING AN AMOUNT OF AIR WHICH ASSISTS IN FORCING ONE BALL AT A TIME THROUGH SAID ORIFICE.

March 23, 1971 w.- T. DE FREITAS 3,572,309

AIR GUN Filed July 24, 1967 FIG. 2

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United States Patent Int. Cl. F nb 11/02 US. Cl. 12411 4 Claims ABSTRACT OF THE DISCLOSURE Air gun for scaring birds and other undesirable creatures, comprising an elongated reservoir wherein a plurality of balls is stored and which can be pressurized. The balls are expelled one by one when the air pressure in the reservoir attains a value capable of forcing one ball through an orifice in the reservoir wall, overcoming the resisting frictional force between the orifice and the ball. Either the balls or the orifice wall can be made elastic or deformable while the other element is made relatively rigid or non-deformable.

In a portion of the reservoir, vertically aligned above said orifice, is a paddle member which is kept sideways by the jet of air which operates the gun, upon the passage of a ball through said orifice. The reservoir is associated with an auxiliary reservoir, by way of a narrow passage, for alternatively storing and delivering an amount of air which assists in forcing one ball at a time through said orifice.

This invention refers to an air gun which is adapted to produce explosions or detonations automatically and at predetermined intervals in order to scare birds and other undesirable creatures the presence or occurrence of which should be avoided in a certain area.

It is an object of the invention to provide a gun which employs an assembly of reservoirs fed by an air compressor, one of said reservoirs containing a series of elastic balls or spheres, each of which, upon being pressed against the muzzle of the gun by the gradually increasing air pressure, and unable to resist such a pressure, is violently expelled through said muzzle, and as a consequence, produces an explosion or loud noise.

The explosion is complete and unique, that is, the evacuation of the compressed air is effected totally and at once because another ball, which forms part of the load of the gun, will not occlude the gun muzzle nor produce a second consecutive shot or explosion before the substantially total evacuation takes place that caused the explosion.

To this end the air gun is provided with a device which locks in place all the balls which are contained in the gun during the complete period in which the com pressed air is exhausted.

The gun is further provided with another device which, upon evacuation of compressed air from the reservoir, positions another ball in the muzzle and presses the same against the muzzle to prevent any leakage of air so that said ball may cause the compressor to raise the pressure inside the gun for a new explosion.

In order that the balls might be re-used and maintained within a container or the like until such use, the air gun may be provided with a device which captures and stores the expelled balls.

The loudness of the explosions or detonations may be increased or decreased at will within a fairly wide range simply by substituting the balls by other balls somewhat bigger or smaller, harder or softer, in accordance with the desired result. The frequency of the explosion may be increased or decreased by admitting more or less 3,572,309 Patented Mar. 23, 1971 compressed air into the gun, by controlling a simple valve associated with the air compressor.

Inasmuch as the mechanism of the air gun comprises only a simple paddle in addition to a small compressor, and the only consumption of energy is the electricity for operating a motor, the gun of the invention is of very economical maintenance.

According to an important feature of the invention, the gun comprises reservoir means which may consist of two reservoir portions and a chamber portion, the first reservoir portion containing compressed air, the second reservoir portion containing the balls together with compressed air, and the chamber portion being fitted with a pivotable paddle member above an orifice which constitutes the muzzle of the gun.

According to another important feature, the gun may have an auxiliary reservoir from which a high-velocity air jet is applied to one side of the paddle member. This is preferably convex, while the air jet delivered from the first reservoir portion impinges upon the concave side of the paddle member.

According to yet another, optional feature of the invention, recovering means may be used in conjunction with the gun, for gathering the balls expelled with each explosion, and comprising a circular tube with two openings, namely for receiving and for discharging the balls. Clamp means may be provided on the tube for diminishing the radius of curvature and for preventing the balls from exiting through the receiving opening during their rotation within the tube. An appropriate container may be disposed underneath the discharging opening, for storing the collected balls. This feature is the subject matter of a divisional application based on the present application, Ser. No. 870,245, filed Sept. 30', 1969.

The various objects, features and attendant advantages of the present invention will become more apparent from the following detailed description of a preferred exemplary embodiment of a bird-scare gun, when considered in conjunction with the accompanying drawing, wherein FIG. 1 represents a somewhat schematical longitudinal sectional view of the air gun according to the invention, showing a portion thereof which produces the shots or explosions;

FIG. 2 is a similarly schematic plan view of an optional recovering device preferably associated with the gun shown in FIG. 1, for capturing and storing the expelled balls before reuse; and

vFIG. 3 is a similarly schematic longitudinal sectional view, somewhat similar to that of FIG. 1 but on an enlarged scale, concentrating on the essential inner mechanism of the gun, as will be described in detail.

As shown in FIG. 1, the bird-scare air gun according to the invention, in a preferred, exemplary embodiment, includes a reservoir 1 for compressed air, a reservoir 2 for elastic balls 7 and compressed air, a chamber of distribution or discharge 3 which connects the two abovementioned reservoirs, and an auxiliary reservoir 4 which is disposed adjacent and linked to the body of reservoir 2 by means of a T-connection 5 (see FIG. 3

At one of its ends, the reservoir 2 is provided with an air-tight door 6 through which the elastic balls 7 may be introduced. The chamber 3 is provided with a washer 8 which has a central perforation or orifice 9 constituting a muzzle for the gun and which has a diameter somewhat smaller than that of the balls 7.

The chamber 3 is provided with a paddle 1-0 capable of swinging a certain angle around a pivot 11, capable of adopting the broken-line position 10' (FIG. 3 also shows that the pivot 11, which can also be a shaft, is sup ported in chamber 3 by a support member 12). The reservoir 4 is connected with the reservoir 2 by means of a tube ice 3 13 of small diameter, located in a washer 14 which separates the reservoirs 2 and 4.

The reservoirs 1, 2 and 4 and the chamber 3 are fed by an air compressor 15. The pressure of the compressor is indicated by a manometer or pressure gage 16.

A used tire tube 17 or the like member, which has an elliptical opening 18 the minor axis of which is slightly bigger than the diameter of one of the balls 7, and the major axis of which is somewhat bigger than said diameter, and another opening 19 having a diameter slightly bigger than that of the balls 7, is preferably arranged undeineath or in the direceion of the gun muzzle 9 so that the center of the elliptical opening 18 falls into a vertical line passing through the center of the muzzle or orifice 9. A box 20 the lid of which has an opening 21 is arranged beneath the tube 17, as shown, so that the openings 19 and 21 align. Some of the less important structural elements will be described somewhat later as the description proceeds.

In short, the operation of the bird-scare gun is as follows: Let us assume that one of the balls 7 is closely adjacent to or closing the muzzle 9 of the gun and that the air compressor 15 raises the pressure of the system to a point such that the one ball is projected outside of the muzzle 9, causing an explosion or detonation. The explosion of the air contained in reservoir 1 will cause the paddle to occupy the position 10', swinging about pivot 11 and preventing, in this position, that the following ball 7 may close the muzzle 9.

As a consequence, the manometric pressure of the system will drop to zero and the air which had been compressed in reservoir 4 will escape, with some delay, through tube 13, and will urge the next ball 7 toward the muzzle 9, once the paddle 10 loses its action as soon as the explosion phase ends. Besides, the air coming from reservoir 4, streaming in at a delivery rate which is large with respect to that of the compressor 15, will re-establish a certain pressure in the system and which, although small, will be enough to cause the next ball 7 to be pressed against the muzzle 9 and to close again the system hermetically.

The compressor 15, constantly in operation, will raise again the pressure of the system until the new ball 7, now located in the orifice 9, is unable to resist the high pressure of the system and provokes a new explosion upon being expelled.

The capture of the balls 7, expedient for economic reasons, will be understood from FIG. 2. Although fully described herein for the sake of completeness, the recovering means constituted by the elements shown in FIG. 2 is not part of the invention claimed herein, and forms the subject matter of the above-mentioned co-pending divisional application. The ball 7 expelled by the gun of FIG. 1 falls into the center of the elliptical opening 18, if the tube 17 is properly positioned with respect to the orifice 9; it gets inside the tube 17 and moves around the inside wall thereof. The ball gradually loses the kinetic energy which was transmitted thereto by the potential energy of the compressed air and, when said kinetic energy is zero and the ball is only subjected to gravity, it is compelled to fall into box 20, passing through openings 19 and 21..

A screw 22 which is threaded in a clamp 23 may be provided to diminish the radius of the curvature of the tube 17 a short distance before the opening 18 so as to avoid that the balls 7 may get out through this opening in the case that they lose their kinetic energy or momentum shortly before reaching the edges of said opening 18.

Having thus explained in general lines the operation of the air gun and of the optional ball recapturing device preferably associated therewith, the actions will now be discussed in more detail which take place during the explosion phenomenon. To this end, the data will be discussed which the inventor gathered in a bird-scare gun built according to the present invention, to verify the materialization of the idea that originated the inven- 4 tion, after eliminating a series of unforeseen results which are the systematic, unavoidable and unseparable companions of all inventions.

In this respect, reference should be had to FIG. 3 which shows a preferred, exemplary embodiment of the air gun built with conventional, readily available parts. For the compressed-air reservoir 1 the inventer used a water pipe 3" in diameter and approximately /2 inches (3.95 meters) long, also shown partially in FIG. 3. For the second reservoir 2, he used the same 3" pipe in a length of approx. 72 ins. (1.83 m.), also partially shown in FIG. 3. He interconnected these two pipes by means of two 3" T-joints, one having its third leg directed downwardly in order to serve as the discharge or distribution chamber 3, and the other having its third leg directed upward (see numeral 5 in FIG. 3) to receive the auxiliary reservoir 4.

In one of the mouths of the first T-joint, the inventor placed a washer 24 having a central opening 1 /2" in diameter and in which he adapted a nozzle 25. In the free mouth of this T-joint he attached the washer 8 having the orifice 9 which constitutes the muzzle of the gun. The diameter of this orifice is approximately 2% in. (54 millimeters) when the diameter of the balls 7 employed in this preferred embodiment is approx. 2 /2 in. (65 mm.).

In the central line of this T-joint, indicated with the letters XX in FIG. 3, he installed the paddle 10 capable of swinging about the pivot 11 mounted on the support 12. In the T-joint 5 which has one leg directed upward, he placed the washer 14 provided with the small tube 13 being in. in diameter.

In the same leg of the T-joint 5, he attached the pipe 4 constituting a reservoir, 3" in diameter and approximately 23 /2 ins. (60 centimeters) long. The free end of pipe 4 is closed by a cap or other conventional means (see FIG. 1).

A small compressor 15, e.g. the kind used for touch-up spray-painting jobs, of /3 HP, was connected to one end of the pipe 1 which end was closed by a cap.

The gun thus built was loaded with thirty solid balls 7 made of very elastic rubber, approxiamtely 2 /2 in. in diameter and weighing approximately 6 /2 ounces (approx. grams) each. These balls are preferably of the type used as toys by children.

The gun took 2 /2 hours to shoot the thirty balls, thus giving a shot or explosion about every five minutes. When the air inlet of the compressor 15 was provided with a cap, having an opening of approx. in. (0.5 mm.) in diameter, the gun took fifteen hours to shoot the thirty balls, thus giving a shot every thirty minutes. The average pressure of the individual shots was 5 atmospheres (manometric).

The computation of the gun dimensions, due to its length and elaboration, is omitted since they are not too critical. Nevertheless, some of the dimensions will be mentioned as a matter of example When deemed useful for the better understanding of further operational features of the inventive bird-scare gun.

Following the examination of the operation, in its most important details, let us consider, with reference to FIG. 3, the three axes X-X, Y-Y' and Z-Z. On axis X-X', the ball 7 shown in solid lines and indicated with the reference x, represents the position that the ball occupies when the air in the chamber 3 is not compressed. In this phase, the paddle 10 will have a more or less restricted space between the washer 24 and the ball x but enough to permit that this ball may freely occupy its place in the muzzle 9. In this phase, the following ball, also shown in solid lines and indicated with the reference Y, will rest against the ball x.

When the air is highly compressed, the ball x will adopt the position and shape shown in broken lines and indicated with the reference x. It Will be noted that the ball is undergoing a pronounced flattening, as shown, and its contour is in contact with the edges of the orifice 9 in washer 8. When the ball x is in this position, the ball Y will move to the position shown in broken lines and indicated by the reference Y, on axis Y-Y.

Naturally, the paddle 10, which can swing freely, inasmuch as it is mounted on the pivot 11, -will fall a certain amount due to the action of gravity, and maintain contact with the ball x. Suddenly, with the increasing pressure transmitted by the air, the ball x will be violently projected through the muzzle 9 of the gun. This of course causes the explosion or detonation, adapted to scare the birds or other creatures.

It is useful to note at this point that, in accordance with the computations referred to above, the median velocity of the air jet at the outlet of pipe 1, and which impinges on the concave face of the paddle 10, is approx. 1085 feet per second (331 meters per second) while the median velocity of the air jet at the outlet of tube 2 is 164 ft./sec. (50 m./sec.).

It should be noted that the pressure exerted by a jet of air on a flat surface perpendicular to its direction varies with the square of its velocity and, on the other hand, that the pressure of a jet of air is approximately four times higher on the concave side of a hollow sphere than on its convex side. For these considerations, the paddle 10 is preferably given a shape which approximates that of a hollow sphere, as illustrated.

Therefore, paddle 10 which is subject to the action of two different jets of air, as described before, will abandon its position to the left of axis X-X' (as viewed in FIG. 3) to occupy the position shown in broken lines and indicated by 10. During this movement, the paddle 10 will shift the ball Y from axis Y-Y' to axis 2-2 and will maintain the ball 7 on this axis until the end of the explosion.

Once the explosion has taken place, the paddle 10, now free of any retention force in the direction to the right of axis X-X', will hang substantially parallel to this axis. The air gushing from reservoir 4 will then move the ball 7 from axis ZZ' to axis X-X' and cause the ball to fall into the muzzle 9.

Inasmuch as the stream of air has a delivery rate relatively high as compared to the very low delivery rate of the compressor, it will communicate to the system a pressure which is low but high enough to press the ball against the muzzle, and thus create a hermetic seal thereat.

According to the computations and tests relative to the preferred exemplary embodiment of the inventive bird-scare gun, the duration of the explosion is of 0.13 second, the pressure decreasing from about 5 atmospheres to atmospheric pressure. According to the same tests, the draining of reservoir 4 from 5 atmospheres to atmospheric pressure takes place in about 1.8 seconds, that is to say 1.7 seconds after the explosion takes place. However, the ball, in its path through positions 7Y-Y', does not fall immediately in the muzzle 9, to position x, and a good portion of the air stored in reservoir 4 leaks to the atmosphere. Assuming a 50% loss of this air, it will still remain, according to the tests and computations, approx. 0.27 cubic foot (0.00775 111. of free air. The three reservoirs 1, 2 and 4 of the gun have a total volume of approx. 1.1 cubic feet (0.0316 m?) with an average charge of balls. This volume of 0.27 cu. ft., distributed in all the reservoirs, will produce a pressure of 1.25 atm. abs. This pressure is sufiicient to retain a ball in the muzzle until the compressor raises the pressure.

It will be apparent that substantially the same effect would be achieved if the balls were rigid or indeforrnable and the gun muzzle were deformable or elastic. It should be borne in mind that the concept of the invention resides in providing an explosion of compressed air in a reservoir the muzzle of which is obturated by a ball having a diameter greater than that of the muzzle, and which will be expelled through said muzzle when the value of the compressed air pressure reaches a predetermined level; and, upon the ball being expelled and having produced the explosion or detonation required for scaring undesirable birds, it will be automatically substituted by another ball which, in turn, will remain waiting until the compressor raises again the pressure in the reservoir, after a period of time to be selected at will, as required, and/or in accordance with the delivery rate of the compressor. The operation of the compressor may be continuous or intermittent, the latter for example if the compressor is controlled by a relay or other conventional control means.

The foregoing disclosure relates only to a preferred exemplary embodiment of the bird-scare air gun, which is intended to include all changes and modifications of the example described, within the scope of the invention as set forth in the appended claims.

It will be understood, for example, by those skilled in the art that the structural details of the gun and of the associated optional recovering device may constructed in other Ways than described. The connection and correlation of the parts may be altered by using different structural elements performing substantially in the same manner.

The inlet door for introducing the balls into the reservoir may be located closer to the orifice than shown in the drawing; the reservoir portion holding the balls may be given a slight inclination so as to allow the balls to roll therealong by gravity; biasing means may be provided for the paddle so as to assist the effect of the two air jets, and other similar minor changes may be made in the invention.

It will be understood from the preceding specification that the auxiliary reservoir 4 must have communication, e.g. by means of the tube 13 of small diameter, with the reservoir portion 2 which holds the balls 7, the reservoir portion 1 for the compressed air, and with the chamber 3 of distribution or discharge. The reservoir 4 may or may not be mechanically connected with any of these last three mentioned parts of the air gun according to the invention.

What I claim is:

1. An air gun, comprising: air-tight reservoir means adapted to contain a plurality of balls of a specific diameter, and provided with an air-tight door through which said balls can be introduced; said reservoir means also having a portion formed with an orifice having a diameter slightly smaller than that of said balls; one of said reservoir-means portion, on the one hand, and said balls, on the other hand, being of an elastic material yielding to the material of the other; said orifice constituting the muzzle of the gun; wherein said orifice does not allow passage of said balls therethrough when the air pressure Within said reservoir means is in the range of atmospheric pressure, and permits the passage of one ball when said balls, one after the other, are seated on said orifice and occlude the same hermetically; and means for periodically compressing the air inside said reservoir means until said air pressure attains a value capable of transmitting to said one ball, when seated on said orifice and pressed thereagainst, a force higher than the resisting frictional force between said orifice and said one ball; whereby said balls are periodically expelled from the gun one after the other, with the production of an explosion which is adapted to scare away birds and other creatures, wherein said reservoir means includes two reservoir portions, one which contains compressed air and another which is elongated and contains said balls together with compressed air, as well as a chamber portion provided with at least three passages; said chamber portion being connected by the first passage with said one reservoir portion, by the second passage with said other reservoir portion, and by the third passage, by way of said orifice, with the atmosphere when said chamber portion is not occluded by one of said balls; and wherein said orifice is disposed intermediate said two reservoir portions; and further comprising a paddle member pivotally suspended within said chamber portion in substantially vertical alignment above said orifice, at least partly in the area occupied by said balls;

7 said paddle member being kept outside the orientation dictated by gravity by a jet of compressed air produced by the explosion upon the passage of said one ball through said orifice, for preventing the ball following said one ball to leave said other reservoir portion and to seat on said 5 orifice while the exposion takes place.

2. The air gun as defined in claim 1, wherein said paddle member has a shape approximating that of a hollow sphere, with its concave side directed toward said one reservoir portion and its convex side facing said other reservoir portion.

3. The air gun as defined in claim 1, further comprising an auxiliary reservoir for compressed air, connected with said reservoir means by way of a fourth passage of small diameter, for gradually storing part of the compressed air which is fed from said chamber portion during a compression phase and for delivering, during a subsequent explosion phase and shortly thereafter, a high-velocity jet of air which causes, after the occlusion of said orifice, a substantial increase in the air pressure within said reservoir means.

4. The air gun as defined in claim 3, wherein the compressed air is derived from the area of said reservoir means occupied by said balls, at a relatively low delivery rate during the compression phase, while the high-velocity jet of air delivered from said auxiliarly reservoir at a relatively high delivery rate acts on a convex portion of said paddle member during the explosion phase and shortly thereafter.

References Cited UNITED STATES PATENTS 2,725,868 12/1955 Foster 1'24-13 2,762,357 9/1956 Foster 12413 387,517 8/1888 Jackson 124-11 1,375,653 4/1921 McLain 124-11 2,238,384 4/1941 Feltman 12411 2,357,951 9/1944 Hale 1'24-11 3,009,703 11/1961 Jentsch 12411 FOREIGN PATENTS 72,279 3/1951 Denmark 124-11 1,185,096 1/19 65 Germany 12411 RICHARD C. PINKHAM, Primary Examiner R. W. DIAZ, JR., Assistant Examiner US. Cl. X.R. 

